+ – Extract: An app that can extract positive/negative sentiment

The functionality of this application is powered by the AlchemyAPI, which uses natural language processing technology and machine learning algorithms to extract semantic meta-data from content, such as information on people, places, companies, topics, facts, relationships, authors, and languages.

The way someone reads what you write may not be how you meant it but there is natural sentiment attached to words and tone in language. This api can evaluate your text or other text you paste in and offer you the sentiment purely based on the words used and their context. Visit site, paste in your text and test your responses before you go burning bridges!